Thinking about sex all the time becomes an honour

THERE are few men who can claim to know the intricacies of sperm like John Aitken.

The reproductive biologist has patented a world first: a chemical contraceptive that kills sperm as well as the bacteria that cause sexually transmitted infections.

''If we could combine fertility regulation with protection against sexually transmitted disease, that would be a wonderful benefit to the population,'' Professor Aitken said.

The contraceptive is having safety trials and, for this research and more, Professor Aitken has been named the 2012 NSW Scientist of the Year.

The British-born biologist first became interested in the biology of sex after reading a book on elephant reproduction when he was a university student. He completed a PhD under the tutelage of the book's author, the reproductive biologist Professor Roger Short.

After a stint at the World Health Organisation in Geneva he realised ''the most important single thing to deal with on the surface of this planet is the unsustainable rate of population growth''.

''[It was then] I became very interested in developing improved forms of contraception.''

The University of Newcastle laureate professor also set himself the difficult task of developing the world's first biological male contraceptive. ''When you designing contraceptives for women, you're trying to stop the ovulation of one egg a month. Men produce 1000 spermatazoa a second,'' he said.

To top it off, Professor Aitken also studies the reproductive workings of domestic animals and has developed a non-surgical technique to sterilise cats and dogs, as well as produced a medium to improve the shelf life of the semen of horses and cattle.

But before he invented methods to prevent pregnancy, his research laboratory at the University of Edinburgh in the mid 1980s tackled the reverse issue: why about one in every 20 males were infertile.

Professor Aitken and his team found that too many free radicals in the body, a process known as oxidative stress, left sperm unable to fertilise an egg.

Since then, small studies suggest the problem can be remedied with antioxidants, found in fruit and vegetables, a treatment that may have enabled thousands of men to become fathers.